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1.
Vjekoslav Živković Martin Arnold Kristijan Radmanović Klaus Richter Hrvoje Turkulin 《Wood Science and Technology》2014,48(2):239-252
Activation spectra of wood under natural irradiation were investigated in detail in this work. The main purpose was to study colour changes on the wood surface over time and into the depth during natural light exposure and thus to further contribute to the optimization of surface-protecting treatments. In a natural weathering test, three 80-μm-thick strips of fir wood forming the surface layer of a wood composite were exposed to light under a series of glass cut-off filters. Samples were withdrawn at intervals and tested for colour changes. Identification of the most detrimental wavebands of light causing photodegradation was performed based on recorded colour changes. With chronological development of exposure, the colour changes shifted ever deeper into the surface and further into the visible region of the spectrum. A relatively narrow waveband from 360 to 435 nm was identified in the activation spectra to be the most active band, causing the greatest proportion of recorded colour changes. However, also visible light of wavelengths up to 515 nm significantly contributed to colour changes of the surface layers. 相似文献
2.
Fulgosi H Jezic M Lepedus H Stefanic PP Curkovic-Perica M Cesar V 《Tree physiology》2012,32(3):346-354
The fate of chloroplast DNA (cpDNA) during plastid development and conversion between various plastid types is still not very well understood. This is especially true for the cpDNA found in plastids of naturally senescing leaves. Here, we describe changes in plastid nucleoid structure accompanied with cpDNA degradation occurring during natural senescence of the free-growing deciduous woody species Acer pseudoplatanus L. Natural senescence was investigated using three types of senescing leaves: green (G), yellow-green (YG) and yellow (Y). The extent of senescence was evaluated at the level of photosynthetic pigment degradation, accumulation of starch and plastid ultrastructure. Determination of cpDNA amount was carried out by in planta visualization with 4,6-diamidino-2-phenylindole, by Southern hybridization, and by dot-blot using an rbcL gene probe. During natural senescence, plastid nucleoids undergo structural rearrangements accompanied by an almost complete loss of cpDNA. Furthermore, senescence-associated protein components exhibiting strong binding to an ～10kbp rbcL-containg cpDNA fragment were identified. This interaction might be important for rbcL expression and Rubisco degradation during the course of natural senescence in trees. 相似文献
3.
Daria Juretic Jelena Puric Hrvoje Kusic Vedrana Marin Ana Loncaric Bozic 《Water, air, and soil pollution》2014,225(10):1-18
The influence of structure on degradation of five halogenated phenols (XPs) by UV/H2O2 process was investigated. The combined influence of type or number of substituents and UV/H2O2 process parameters (pH and [H2O2]) on the degradation kinetics of 2-fluorophenol (2-FP), 2-chlorophenol (2-CP), 2-bromophenol (2-BP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) was studied using modified miscellaneous 33 full factorial design and response surface modeling (RSM). Studied XPs obey first-order degradation kinetics within the investigated range of process parameters. Determined degradation rate constants (k obs) were correlated with process and structural parameters by the quadratic polynomial models. Analysis of variance (ANOVA) demonstrated RSM models’ accuracy and showed that, in addition to pH and [H2O2], model terms related with the pollutant structure are highly influential. k obs of mono-XPs follow the decreasing order 2-FP, 2-CP, and 2-BP, while CPs follow the decreasing order 2-CP, 2,4-DCP, and 2,4,6-TCP. Biodegradability (biochemical oxygen demand (BOD)5/chemical oxygen demand (COD)) and toxicity (TU) were evaluated prior to the treatment and at the reference time intervals. The observed differences are correlated with the structural characteristics of studied XPs. 相似文献
4.
The atomic electron orbitals that underlie molecular bonding originate from the central Coulomb potential of the atomic core. We used scanning tunneling microscopy and density functional theory to explore the relation between the nearly spherical shape and unoccupied electronic structure of buckminsterfullerene (C60) molecules adsorbed on copper surfaces. Besides the known pi* antibonding molecular orbitals of the carbon-atom framework, above 3.5 electron volts we found atomlike orbitals bound to the core of the hollow C60 cage. These "superatom" states hybridize like the s and p orbitals of hydrogen and alkali atoms into diatomic molecule-like dimers and free-electron bands of one-dimensional wires and two-dimensional quantum wells in C60 aggregates. We attribute the superatom states to the central potential binding an electron to its screening charge, a property expected for hollow-shell molecules derived from layered materials. 相似文献
5.
The coupling of electron and nuclear motions in ultrafast charge transfer at molecule-semiconductor interfaces is central to many phenomena, including catalysis, photocatalysis, and molecular electronics. By using femtosecond laser excitation, we transferred electrons from a rutile titanium dioxide (110) surface into a CH3OH overlayer state that is 2.3 +/- 0.2 electron volts above the Fermi level. The redistributed charge was stabilized within 30 femtoseconds by the inertial motion of substrate ions (polaron formation) and, more slowly, by adsorbate molecules (solvation). According to a pronounced deuterium isotope effect (CH3OD), this motion of heavy atoms transforms the reverse charge transfer from a purely electronic process (nonadiabatic) to a correlated response of electrons and protons. 相似文献
6.
Wael A Khamas Hrvoje Smodlaka Jessica Leach-Robinson Lauren Palmer 《Acta veterinaria Scandinavica》2012,54(1):46
Background
Pinnipeds have a thick blubber layer and may have difficulty maintaining their body temperature during hot weather when on land. The skin is the main thermoregulatory conduit which emits excessive body heat.Methods
Thorough evaluation of the skin histology in three pinniped species; the California sea lion-Zalophus californianus, the Pacific harbor seal-Phoca vitulina richardsi, and the Northern elephant seal-Mirounga angustirostris, was conducted to identify the presence, location and distribution of skin structures which contribute to thermoregulation. These structures included hair, adipose tissue, sweat glands, vasculature, and arteriovenous anastomoses (AVA). Thermal imaging was performed on live animals of the same species to correlate histological findings with thermal emission of the skin.Results
The presence and distribution of skin structures directly relates to emissivity of the skin in all three species. Emissivity of skin in phocids (Pacific harbor and Northern elephant seals) follows a different pattern than skin in otariids (California sea lions). The flipper skin in phocids tends to be the most emissive region during hot weather and least emissive during cold weather. On the contrary in otariids, skin of the entire body has a tendency to be emissive during both hot and cold weather.Conclusion
Heat dissipation of the skin directly relates to the presence and distribution of skin structures in all three species. Different skin thermal dissipation patterns were observed in phocid versus otariid seals. Observed thermal patterns can be used for proper understanding of optimum thermal needs of seals housed in research facilities, rescue centers and zoo exhibits. 相似文献7.
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9.
Jerko Gunjaca Ivica Buhinicek Mirko Jukic Hrvoje Sarcevic Antun Vragolovic Zdravko Kozic Antun Jambrovic Ivan Pejic 《Euphytica》2008,161(1-2):165-172
Growing numbers of candidate varieties, decrease of their variability for morphological traits, and internationalization of
the national list all contribute to excessive increase of the trial costs, thus creating the need for the improvement of current
variety evaluation procedures, especially regards their distinctness, Uniformity, and Stability (DUS) component. Due to rapid
advancement in molecular techniques, the use of molecular markers in DUS testing as a complement to, or replacement of, morphological
observations became the subject of great interest in scientific studies, and consequently topic for discussion within International
Union for the Protection of New Varieties of Plants (UPOV). In order to explore the potential of simple sequence repeat (SSR)
markers for distinctness tests, present study involved set of 41 maize inbred lines that were scored for 32 DUS characters
prescribed by UPOV and genotyped at 28 SSR loci. Results were largely in favor of the use of molecular markers, revealing
or confirming their already known advantages over morphological markers like better consistency with the pedigree, and relatively
higher discriminative power. However, their integration into DUS testing protocols still depends upon resolving of several
important issues. 相似文献
10.
Maksimir 3 Synthetic (M3S) maize population was developed at the Faculty of Agriculture University of Zagreb by intercrossing
inbred lines, whose origins trace back to several open-pollinated varieties and local populations from different regions of
the former Yugoslavia. The population was subjected to two cycles of selfed progeny recurrent selection for grain yield. The
objectives of this study were: (i) to determine genetic distances among the parental inbred lines of the M3S population (M3S
progenitors), the M3S population before and after two cycles of recurrent selection, and elite inbred lines representing the
BSSS and Lancaster heterotic group; and (ii) to examine the effect of two cycles of recurrent selection on allele frequency
changes in the population. Nine M3S progenitors, three BSSS lines, and three Lancaster lines were genotyped at 24 SSR loci,
out of which nine randomly chosen loci were used for genotyping 96 individuals from both C0 (the M3S population before selection)
and from C2 (M3S population after two cycles of selection). A total of 101 alleles were detected across 24 loci in the 15
lines, whereas 83 alleles were found in the nine M3S progenitors. Among the latter 83 alleles 31 were unique, i.e. found only
in one of the progenitors. Mean genetic distance among nine M3S progenitors was 0.61 indicating a broad genetic base of the
M3S population. High mean genetic distance was found between M3S progenitors and BSSS lines (0.69) and M3S progenitors and
Lancaster lines (0.71). This indicates that the M3S population represents a germplasm source unrelated to both the BSSS and
Lancaster germplasm. Mean genetic distance between the M3S population and BSSS as well as Lancaster lines decreased slightly
after two cycles of recurrent selection suggesting the need to introduce testers from both groups in future selection in the
M3S population in order to maintain heterotic complementarity of the M3S population to these groups. A test of selective neutrality
identified several non-neutral loci in the population whose allele frequency changes from the C0 to the C2 cannot be explained
by genetic drift. The majority of non-neutral alleles, whose frequency increased after two cycles of selection, were present
in at least one line from the BSSS or Lancaster heterotic group. 相似文献